Respect the na argument in write_csv2

We inadvertently removed the na handling by calling `format()`, which
changes all NAs to the characters "NA".

Fixes #928

NEWS.md

@@ -1,5 +1,7 @@
 # readr 1.2.1.9000
 
+* `write_csv2()` now properly respects the `na` argument (#928)
+
 * Fixes compilation with multiple architectures on linux (#922).
 
 * Fixes compilation with R < 3.3.0

R/write.R

@@ -226,7 +226,16 @@ stream_delim <- function(df, path, append = FALSE, bom = FALSE, ..., quote_escap
 change_decimal_separator <- function(x, decimal_mark = ",") {
   stopifnot(is.data.frame(x))
   numeric_cols <- vapply(x, is.numeric, logical(1))
-  x[numeric_cols] <- lapply(x[numeric_cols], format, decimal.mark = decimal_mark)
+
+  format_seps <- function(x, decimal_mark) {
+    nas <- is.na(x)
+    x <- format(x, decimal.mark = decimal_mark)
+    x[nas] <- NA_character_
+    x
+  }
+
+  x[numeric_cols] <- lapply(x[numeric_cols], format_seps, decimal_mark)
+
   x
 }
 

tests/testthat/test-write.R

@@ -14,8 +14,8 @@ test_that("a literal NA is quoted", {
 })
 
 test_that("na argument modifies how missing values are written", {
-  df <- data.frame(x = c(NA, "x", "."))
-  expect_equal(format_csv(df, na = "."), "x\n.\nx\n\".\"\n")
+  df <- data.frame(x = c(NA, "x", "."), y = c(1, 2, NA))
+  expect_equal(format_csv(df, na = "."), "x,y\n.,1\nx,2\n\".\",.\n")
 })
 
 test_that("read_delim/csv/tsv and write_delim round trip special chars", {
@@ -142,6 +142,11 @@ test_that("write_csv2 and format_csv2 writes ; sep and , decimal mark", {
   expect_equivalent(df, suppressMessages(read_csv2(filename)))
 })
 
+test_that("write_csv2 and format_csv2 writes NA appropriately", {
+  df <- tibble::data_frame(x = c(0.5, NA, 1.2), y = c("a", "b", NA))
+  expect_equal(format_csv2(df), "x;y\n0,5;a\nNA;b\n1,2;NA\n")
+})
+
 test_that("Can change the escape behavior for quotes", {
   df <- data.frame(x = c("a", '"', ",", "\n"))